Elastic yarn and method of making the same



July 23, 1963 w. D. SMITH 3,098,347

ELASTIC YARN AND METHOD OF MAKING THE SAME Filed March 20, 1962 FIGI. A

L V V 5 i i T FIG. 2. ,9

A III E INVENTOR: WILBERT D. SMITH ATT YS.

United States Patent Office Patented July 23, 1963 3,098,347 ELASTICYARN AND METHOD OF MAKKNG THE SAME Wilbert D. Smith, Philadelphia, Pa.,assignor to Parayarn Elastic 60., Philadelphia, Pa, a corporation ofPennsylvania Filed Mar. 20, 1962, Ser. No. 181,020 Claims. (Cl. 57152)The present invention relates to a method of making a truly balanced,single cover elastic yarn and the truly balanced elastic yarn producedthereby.

Elastic yarns are usually formed by intertwisting an elastic filamentand an inelastic thread of a synthetic material such as rayon, nylon orthe like or Wrapping the filament with the thread. Prior to the presentinvention, it was thought that the solution to the problem of making abalanced elastic yarn was to pretwist one or both elements of theelastic yarn proir to intertwisting or wrapping to produce the finishedelastic yarn. For example, in accordance with a prior method for formingelastic yarn, the elastic filament is given an initial twist in onedirection and the inelastic thread is given an initial twist in adirection opposite the twist of the elastic filament and then theelastic filament and inelastic thread are intertwisted so that thecomposite yarn is formed of closely axially compacted interlockingalternating convolutions of the filament and thread. In accordance withanother prior method for forming elastic yarn, the elastic filament ispretwisted and stretched and while in this condition, a pretwistedinelastic thread is spiralled rather than twisted on to the elasticfilament.

The major disadvantage of elastic yarns produced by the above priormethods is that they have a tendency to kink or curl up when in arelaxed condition. Because of this kinking tendency, the elastic yarnsare ditficult to handle in weaving apparatus or the like and the clothor fabric produced thereby is of an inferior quality.

Further, pretwisting of the filament and thread induces stress in thefinished elastic yarn which may contribute to premature failure of theelastic yarn.

In accordance with the present invention, a new and improved method isprovided for making a single cover elastic yarn wherein the yarnproduced thereby is a truly balanced yarn. In accordance with thepresent invention, an inelastic cover thread is helically wound about anelastic core filament while the elastic filament and inelastic threadare maintained in a substantially nntwisted, unstressed condition. Theconvolutions of the cover thread are closely compacted axially of theelastic core filament to provide a well covered elastic yarn. By thepresent method, pretwisting of the filament and thread are eliminatedand I have found that by this method there is produced a truly balancedelastic yarn, one which does not tend to kink or curl up in its relaxedcondition. A truly balanced elastic yarn facilitates handling in weavingapparatus or the like and the cloth or fabric produced thereby is of animproved quality. Further since the filament and thread are not stressedby pretwisting, there is less chance of the elastic yarn failingprematurely. The present invention may be employed to make trulybalanced, single cover elastic yarns having an elongation fallinganywhere in the expanded range of from about 100 percent to 300 percentas desired whereby the elastic yarn of the present invention has a broadrange of commercial application.

With the foregoing in mind, an object of the present 7 invention is toprovide a new and improved, simple and effective method for producing atruly balanced elastic yarn.

Another object of the present invention is to provide a truly balancedelastic yarn which does not tend to kink or curl up and accordingly ismuch easier to process and wherein cloth or fabric made from the yarn isof improved quality.

A still further object of the present invention is to provide a simpleand effective method for producing a truly balanced single cover elasticyarn which is more durable than similar yarns produced by prior methods.

These and other objects of the present invention and the variousfeatures and details thereof are set forth more fully hereinafter withreference to the accompanying drawings, wherein:

FIG. 1 shows diagrammatically a piece of inelastic thread in a relaxed,nntwisted condition;

FIG. 2 shows a piece of elastic filament in its nntwisted relaxedcondition;

FIG. 3 shows an elastic yarn produced in accordance with the presentinvention; and

FIG. 4 illustrates diagrammatically apparatus for carrying out themethod of the present invention.

In accordance with the present invention, an nntwisted inelastic coverthread A is helically wrapped around an untwisted elastic core filamentB to produce a truly balanced, single cover elastic yarn C as shown inFIG. 3. The elastic yarn is characterized by a continuous series ofuntwisted, engaging convolutions of cover thread which are closelycompacted axially of the nntwisted core filament to produce a trulybalanced, well covered elastic yarn.

There is shown in FIG. 4 an example of apparatus for carrying out themethod of the present invention to produce a truly balanced, singlecover elastic yarn. As illustreated, the apparatus includes a pair ofconventional upper and lower coaxially mounted rotatable spools 10 and12 having Wound thereon the inelastic cover thread A and elastic corefilament B respectively. The spool 10 is mounted for rotation about avertically disposed stationary tubular spindle 14 secured to a rigidsupport 16. The support 16 mounts a depending C-shaped bracket 17 havinga tubular bushing 19 which is axially aligned with and spaced from thelower end of the tubular spindle 14 and which serves to guide theelastic core filament B in its path from the spool 12 through thespindle 14. The spool 10 is rotated by means of a pulley 13 dependingfrom the spool 19 and a belt 26 connecting the pulley with suitabledrive means. A central disc 21 rests on the upper flange 22 of the spool10 and mounts a radially projecting arm 23 which has at its outer end aneye or flyer 24 through which the inelastic cover thread A passes as itis discharged from the spool It] to a point X Where it is wrapped aroundthe core filament B to produce the finished yarn.

The spool 12 is mounted for rotation on a stationary spindle 26 securedto a rigid support 28 and is rotated by suitable drive means similar tothat of the spool 10 in cluding a pulley 3t and a belt 32.

It is noted that the cover thread A and the core filament B areinitially supplied from a manufacturer on packages in an nntwistedcondition. Thereafter the cover thread A and the core filament B each istaken off of the package over end and wound onto its respective spool 10and 12. During the process of transferring the cover thread A and corefilament B from the package to the spools and 12 respectively, apredetermined number of turns are inserted into the core filament andcover thread on their respective spools. The spools 10 and 12 are thenpositioned on the spindles 14 and 26 respectively so that as the coverthread A and core filament B are taken off over end as shown in FIG. 4,the predetermined number of turns inserted in the cover thread A andcore filament B are taken out. Thus as the core filament B is wrapped atthe point X with the cover thread A, both the cover thread and the corefilament are untwisted.

In setting up the apparatus described to produce a truly balancedelastic yarn, the free end of the core filament B is threaded throughthe bushing 19 up through the spindle 14, passed over a guide roller 34and secured to a take up roll 35. The free end of the inelastic coverthread A is then secured to the core filament B in the region X. Thespool 12 is then rotated in a direction to unwind the elastic corefilament B and the spool 10 is rotated in a directoin to unwind thecover thread A. At the point X the core filament B is in substantiallyunstressed, tensionless condition and is helically wrapped with thecover thread A. The finished elastic yarn C then passes over the guideroller 34 and is wound on to the take up roll 35. The take up roll 35 isrotated by suitable drive means to provide a constant linear feed of thefinished yarn. Further, the spwd of rotation of the take up roll 35 andcore filament feed are correlated in a predetermined manner to maintainthe elastic core filament B taut in the region X where it is beingwrapped. By this arrangement, an elastic yarn is produced which ischaracterized by an untwisted core filament B and an untwisted coverthread A and accordingly is a truly balanced, well covered yarn whichdoes not ten-d to curl up or kink. It is noted that for a given type ofcover thread A and core filament B, the take up roll 35 is rotated at apredetermined rate when making a long stretch yarn and at a slightlygreater rate when making a short stretch yarn.

In accordance with the present invention, truly balanced, single coverelastic yarns can be produced having an elongation falling anywhere inthe expanded range of from about 100 percent to 300 percent as desired.In the present instance, this is accomplished by controlling selectivelythe relative speeds of rotation of the spools 10 and 12 for a given typeof elastic filament and inelastic thread. For example, if it is desiredto make a short stretch elastic yarn having a core filament B made of aSpandex yarn such as Lycra, and an inelastic cover thread A such as a 50single cotton, the bottom spool 12 is rotated at about 4000 r.p.m.s andthe top spool 10 is rotated at 8000 r.p.m.s. Lycra has about a 600percent elongation in its substantially relaxed condition on the spool12 and as it is unwound from the bottom spool 12, it is stretched andpermanently set to about a 300 percent elongation by virtue of the airresistance which as shown in FIG. 4, produces a ballooning in the corefilament in the region of the upper flange of the spool 12. Thereafterthe core filament B is helically wrapped by the cover thread A at thepoint X while the core filament B is in a substantially unstressed,tensionless condition whereby the speed of the spool 10 effects apredetermined desired number of convolutions of the cover thread on thecore filament to produce a truly balanced elastic yarn having about a100 percent elongation. Employing the same materials to produce a longstretch elastic yarn, the bottom spool 12 is rotated at 7000 r.p.rn.sand the top spool is rotated at about 5500 r.p.m.s.

It is to be understood that the word untwisted as used herein or in theclaims in connection with the cover thread A means that no twist isimparted to the cover thread during making of elastic yarn in accordancewith the present invention and that it is not twisted in the finishedelastic yarn. However, where a cover thread such as a multifilameutcotton is used, the fibers comprising the thread may be intertwisted inthe process of making the cotton to hold them together.

Manifestly, other types of elastic materials and inelastic threads maybe employed as the core filament and cover thread respectively toproduce truly balanced elastic yarns within the teaching of the presentinvention. Additionally, while the method of the present invention hasbeen illustrated and described herein in connection with a particularapparatus, it is of course to be understood that modifications may bemade therein within the scope of the following claims.

I claim:

1. A truly balanced elastic yarn comprising an elastic untwisted corefilament and an inelastic untwisted cover thread helically wound aboutthe core filament.

2. An elastic yarn as claimed in claim 1 wherein the convolutions of thecover thread are closely compacted axially of the core filament toprovide a truly balanced well covered elastic yarn.

3. A method of making a truly balanced elastic yarn comprising helicallywinding an untwisted cover thread about an untwisted elastic corefilament.

4. A method of making a truly balanced elastic yam from an elastic corefilament and an inelastic cover thread each wound on a spool consistingof the steps of rotating the spools in a direction to unwind the corefilament and cover thread from their respective spools in an untwistedcondition and helically winding the untwisted inelastic cover threadabout the untwisted core filament.

5. A method of making a truly balanced elastic yarn from an inelasticcover thread wound on a first spool rotatably mounted on a tubularspindle and an elastic core filament wound on a second spool consistingof the steps of rotating the spools in a direction to unwind the corefilament and cover thread from their respective spools in an untwistedcondition, passing the core filament through the tubular spindle andhelically winding the untwisted inelastic cover thread about theuntwisted core filament after the core filament has passed through thespindle.

6. A method of making a truly balanced elastic yarn from an inelasticcover thread wound on a first spool rotatably mounted on a tubularspindle and an elastic core filament wound on a second spool consistingof the steps of rotating the spools in a direction to unwind the corefilament and cover thread from their respective spools in an untwistedcondition, passing the core filament through the tubular spindle,helically winding the untwisted inelastic cover thread about theuntwisted core filament after the core filament has passed through thespindle and winding the finished elastic yarn on a take up roll.

7. A method of making a truly balanced elastic yarn from an inelasticcover thread wound on a first spool rotatably mounted on a tubularspindle and an elastic core filament wound on a second spool consistingof the steps of rotating the spools in a direction to unwind the corefilament and cover thread from their respective spools in an untwistedcondition, passing the core filament through the tubular spindle,helically winding the untwisted inelastic cover thread about theuntwisted core filament after the core filament has passed through thespindle, rotating a take up roll in a direction to wind the finishedelastic yarn thereon and controlling the rotation of the take up roll,core filament and cover thread spool to produce a truly balanced elasticyarn characterized by an untwisted core filament and untwisted coverthread.

8. A method of making a truly balanced elastic yarn consisting of thesteps of helically winding an untwisted cover thread about an untwistedelastic core filament and maintaining the core filament in the regionwhere it is wrapped with the cover thread in a substantially unstressed,tensionless condition.

9. A truly balanced elastic yarn as claimed in claim 1 wherein the corefilament is a Spandex yarn and said cover thread is cotton.

6 10. A truly balanced elastic yarn as claimed in claim 1 2,076,270Harris Apr. 6, 1937 wherein the core filament is a Spandex yarn and said2,690,047 Long Sept. 28, 1954 cover thread is nylon. 3,009,311 Kung-ChihWang Nov. 21, 196 1 References Cited in the file of this patent 5101L302 Rupprecht 1961 UNITED STATES PATENTS FOREIGN PATENTS 2,061,021Chittenden et a1. Nov. 17, 1936 726,479 Great Britain Mar. 16, 1955

1. A TRULY BALANCED ELASTIC YARN COMPRISING AN ELASTIC UNTWISTED COREFILAMENT AND AN INELASTIC UNTWISTED COVER THREAD HELICALLY WOUND ABOUTTHE CORE FILAMENT.